Methods of treatment of the dental pulp and filling root canals using water-based material

ABSTRACT

A dental composition comprising: a) about 1 to about 80% by weight of particulate material including: (i) calcium silicate, calcium aluminate, tetracalcium aluminoferrite, calcium phosphate, calcium sulfate, silica, alumina, calcium oxide, calcium hydroxide, or mixtures thereof; wherein the particulate material has an average particle size of less than 40 microns; and b) about 1 to about 50% by weight liquid carrier including: (i) water-soluble polymer, and (ii) water.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. Ser. No.14/149,340, filed on Jan. 7, 2014, which is a Continuation applicationof U.S. Ser. No. 12/069,359, filed on Feb. 8, 2008, which claims thebenefit of U.S. Provisional Patent Application Ser. No. 60/900,475having a filing date of Feb. 9, 2007, the entire contents of which arehereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to improved dental compositionsfor treating the pulp and root canals in a tooth. The compositionscontain a mixture of particulate materials such as calcium silicate,calcium aluminate, calcium hydroxide, and hydroxyapatite; variousorganic water-soluble polymeric materials; and surfactants that interactwith the polymeric materials.

2. Brief Description of the Related Art

The inner portion of a tooth includes a pulp cavity that contains softliving tissue or the “pulp” of the tooth. The pulp includes connectivetissue, blood vessels, cells, and nerve endings. The pulp cavitycomprises an upper pulp chamber and root canals that extend to the apexor apical section of the tooth deeper into the jaw. The outer (visible)portion of the tooth is referred to as the crown and has a covering ofenamel. The hard enamel protects softer dentinal tissues in the upperportion of the tooth. The enamel consists of a hard, calcium-basedsubstance, hydroxyfluorapatite. The dentin tissue contains a matrix ofminute hydroxyapatite tubules interspersed with collagen fibers thatsurround and protect the tooth pulp. The outer (non-visible) portion ofthe tooth root is covered with cementum, a thin hard tissue that joinsthe root to the surrounding bone through Sharpey's fibers. Dental decay,or caries, is caused by bacteria accumulating on teeth and forming abiofilm (plaque). The biofilm produces acids that dissolve and weakenthe hydroxyapatite of the tooth, thereby causing decay.

When dental caries are found in the enamel portion of a tooth, a dentalprofessional will remove the caries to prevent further decay of thetooth. Then, the cavity is “filled” with a composite resinous materialor amalgam filling. However, in some instances, the dental caries may beso deep that it penetrates to the dentin tissue. At this point, thebacteria and other microorganisms can migrate rapidly into the pulptissue causing infection and inflammation. As a result, abscesses orinflammation may form in the pulp, and eventually in the periapicaltissues surrounding the root apex. Provided that the dental disease isnot too progressed, dental professionals will use root canal treatmentprocedures to remove the infected tissue from the tooth and replace itwith an inert, biocompatible material. Otherwise, extraction of thetooth might be required.

The root canal system of a tooth is complex and many treatment methodscan be used depending upon the condition of the patient and approach ofthe practitioner. In general, root canal treatment methods first involvedrilling an opening in the crown of the tooth to provide access to thepulp cavity. Then, endodontic files are used to remove the pulp andclean and shape the root canals. The files are used with an irrigant.After using the files, an irrigant may be used to remove the smear layercreated by the files. A sealer is coated on the wall of the root canalsand then, the root canals are filled with a filling material. Thissealing of the roots ideally prevents bacteria and other microorganismsfrom re-entering and causing infection of the living tissue surroundingthe root tip. As a final step, the pulp chamber and opening in the crownof the tooth is sealed with a dental restoration such as a fillingmaterial. Preferably a permanent crown is placed over the opening in thetooth, such crowns being made of metal, porcelain-enameled metal,polymer-veneered metal, or ceramic. A post may be placed in the root forstability of the crown, although this is usually done after the rootcanal procedure, and before the crown is made.

One method for filling root canals involves using naturally occurring orsynthetic gutta-percha, an isomer of rubber. Gutta-percha points havinga tapered conical shape can be prepared, and these points can be fittedinto the root canal. Historically, one older treatment method involvesusing single cones of gutta-percha. In this method, zinc oxide-eugenolcement sealer is first placed in the root canal. Then a single unheatedcone of gutta-percha is fitted into the root canal. New techniques havebeen developed including cold lateral compaction, where multiplegutta-percha cones are compressed into the root canal after a root canalsealer is placed on the canal walls. More recently, procedures employingheated gutta-percha are being used that allow the gutta-percha to flowso that it can move into the minute intra-canal spaces, lateral canals,accessory canals, and other irregularities of the canals. One suchtechnique uses a metal or plastic carrier coated with a layer ofgutta-percha. The carrier includes a metal or plastic shaft with adistal tapered end that extends from a cylindrically shaped handle. Thecarrier transports the gutta-percha into the working length of the canaland compacts the gutta-percha into lateral and accessory canals. Oncethe carrier is stabilized in the canal, the upper handle portion andshaft is severed at a point level to the orifice of the canal using adental bur or other sharp instrument. The lower portion of the shaftremains in the canal encased in the hardened gutta-percha. Other warmgutta-percha techniques include the compaction of gutta-percha that isextruded into the canal after a root canal sealer is placed.Combinations of cold and warm gutta-percha sealing techniques also canbe used.

Other root canal treatment methods involve using portland cement torepair root defects such as iatrogenic perforations, or when apicalsurgery is performed to fill the root end. In general, portland cementcontains a compound formed from calcia, silica, alumina, and iron oxidematerials. Portland cement is commonly gray, but white versions, withlower iron content are known. The portland cement is combined with waterto form a slurry-like composition that is introduced into the root canaldefect. The composition solidifies to seal the canal. When portlandcement materials are used to fill or seal the root canals, the cementparticulates should have a small particle size. The fineness of a cementis represented by the surface area and one measurement thereof is theBlaine Number representing the ratio of the cement's particle surfacearea to its weight (square centimeters of surface per gram).

Torabinejad et al., U.S. Pat. Nos. 5,769,738 and 5,415,547 describeusing a portland cement composition having a Blaine number in the rangeof 4,000 to 5,500 cm²/gram for various surgical and non-surgical rootcanal treatment procedures including sealing root canals, performingapicoectomies, and repairing root canal perforations. The '738 and '547patents disclose combining the portland cement with water to form acomposition that is introduced into the root canal. There is nodisclosure in the '738 and '547 patents for making a compositioncontaining water-soluble polymeric materials, surfactants, and portlandcement.

In addition to portland cements, other biomedical cements have beendeveloped for medical and dental applications. For example, Lu et al.,US Patent Application Publication US 2007/0098811 discloses a biomedicalcement containing at least one phosphate compound and at least onecalcium silicate compound that does not contain any aluminum ormagnesium compounds. Preferably, the cement contains 45 to 80 weightpercent calcium oxide; 10 to 35 weight percent silica; and 1 to 30weight percent phosphate. Water-soluble polymeric materials are notadded to the cement. Hydroxyapatite can be added to formhydroxyapatite/calcium silicate hydrate gel in situ at room temperature.

Kawahara et al., U.S. Pat. No. 4,647,600 discloses a dental cement thatcan be used for pulp-capping, base lining, root canal filling, and otherapplications. The composition is made of two parts. Part A comprises atleast two powders—100 parts by weight of a powder containing calciumoxide and alumina; and 2 to 70 parts by weight of calcium hydroxidepowder. According to the '600 patent, it is important that the powderparticulates be surface-treated with organic and/or inorganic acids toincrease the flowability of the particulate during mixing. Part Bcomprises an aqueous solution containing 0.01 to 70 wt. % of awater-soluble, high molecular weight substance (for example, polyvinylpyrrolidone, polyethylene oxide, sodium polyacrylate, and sodiumpolymethacrylate.) Dental cements containing powder particulate,water-soluble polymeric materials, and surfactants are not disclosed inthe '600 patent.

Kawahara et al., U.S. Pat. No. 4,689,080 discloses a composition ofalumina cement that can be used in dental pulp capping, root canalfilling, sealing, alveolar bone reconstruction, and the like. Thealumina cement is an industrial cement that can be mixed with othermaterials. The composition consists of: a) industrial calcium aluminatepowder; b) calcium type powder hardening retarder such as calciumhydroxide, calcium chloride, or calcium oxide; and c) water-solublepolymer such as polyvinyl alcohol, polyvinyl pyrrolidone, gum arabic,acrylic acid, glycerine, sodium metasilicate, low-molecular fatty acid,or hydrophobic natural resin. According to the '080 patent, it isimportant that a hardening retarder, preferably calcium hydroxide, beadded to the mixture. The calcium hardening retarder is added in a ratioof 1-20 parts by weight to 100 parts by weight of alumina cement powder.Compositions containing powder particulate, water-soluble polymericmaterials, and surfactants are not described in the '080 patent.

Jefferies and Primus, PCT International Application Publication No. WO2005/087178 discloses a polymer-infiltrated structure of calcium-basedcement that can be potentially used as a pulp capping agent, root repairmaterial, root canal sealer, and other clinical products. Aself-etching/self-priming dental adhesive can be applied to the surfaceof an unset dental cement material to form a polymer-infiltratedstructure. The surface infiltration permits stabilization of the cementbefore it fully sets. In another example, a portland cement material isdescribed as being mixed with a solution of 2-10% polyvinyl pyrrolidonehaving a molecular weight between 40,000 and 1,300,000. There is nodisclosure of using any surfactants in the composition.

Another material that is used in surgical and non-surgical root canalprocedures is ProRoot™ MTA root repair material available from DentsplyTulsa Dental Specialties (Tulsa, Okla.). ProRoot MTA material has acomposition similar to portland cement and does not contain anywater-soluble polymeric materials. Particularly, the MTA materialincludes fine hydrophilic particles of dicalcium silicate, tricalciumsilicate, tricalcium aluminate, tetracalcium aluminoferrite, calciumsulfate dihydrate, and bismuth oxide that are combined with water toform a cement-like material. The MTA material is available in gray andwhite colored formulations. The oxides used in the MTA powder are of thehighest purity to ensure that no heavy metals are included and used inthe body. MTA root canal repair material is used in a wide variety ofclinical applications. Particularly, the cement-like material has beenused to repair root canal perforations during root canal therapy; fillroot ends; treat injured pulps in procedures known as pulp capping andpulpotomy, and repair root resorption.

Although MTA materials are generally effective in surgical andnon-surgical root canal procedures, some dental literature hascriticized these materials for having poor handling properties and asand-like feel. There is a need for a composition having improvedhandling and placement properties. The composition should have goodworking time so that the dental practitioner can handle and place thematerial more effectively and preferably the material will start to setbefore the dental procedure is completed. Ideally, the material shouldpromote the healing or repair of the pulp-tissue or the tissuesurrounding root canal tips. The material should also provide a tightseal against the root canal dentin to prevent bacterial migrationthrough the root canal. The present invention provides such improvedmaterials.

SUMMARY OF THE INVENTION

The present invention provides improved compositions for treating thepulp and root canals in a tooth. The compositions can be used in variousapplications including the repair of root canal perforations, filling ofroot ends, treatment of injured pulps and repair of root resorption. Ingeneral, the compositions are made from a powdered particulate materialand a liquid carrier comprising water-soluble polymers and water.Various particulate material, polymeric materials can be used inaccordance with this invention. For example, the particulate materialcan be selected from the group consisting of calcium silicate, calciumaluminate, tetracalcium aluminoferrite, calcium phosphate, calciumsulfate, silica, alumina, calcium oxide, calcium hydroxide, and mixturesthereof. The powdered particulate is optionally blended withhydroxyapatite, a form of calcium phosphate, and other compounds such asradiopaque materials. Preferably, the particulate has a surface area ofat least 0.5 m²/g and more preferably greater than 0.9 m²/g. Examples ofsuitable water-soluble polymeric materials that can used in thecompositions include polyvinyl alcohols, polyvinyl-pyrrolidone (PVP),partially hydrolyzed polyvinyl acetates, (PVAc), polyacrylic acid (PAA),and polymethacrylic acid (PMA), and mixtures thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a bar graph showing fluid microleakage data in root canalsystems treated with a first composition of this invention versus acomparative root canal sealer material.

FIG. 2 is a bar graph showing fluid microleakage data in root canalsystems treated with a second composition of this invention versuscomparative root canal sealer materials.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides new compositions suitable for use inhealing diseased teeth. The compositions are particularly suitable foruse in treating root canals. In addition, the compositions may be usedfor cavity lining or pulp-capping of carious teeth, treatment oftraumatized teeth, or any procedure where bacterial leakage is to beminimized between the coronal and apical areas.

The composition of this invention is made from two parts. Part A of theproduct is particulate material selected from the group consisting ofcalcium silicate, calcium aluminate, tetracalcium aluminoferrite,calcium phosphate, calcium sulfate, silica, alumina, calcium oxide,calcium hydroxide and mixtures thereof. Such particulate materials andmixtures thereof may be referred to herein as “dentalcrete” particulate.The dentalcrete particulate can be optionally blended withhydroxyapatite, a form of calcium phosphate, particulate. Compositionscontaining a combination of dentalcrete and hydroxyapatite particulatemay be referred to herein as “phoscrete” particulate. Other compoundssuch as bismuth oxide, barium sulfate, tantalum oxide, cerium oxide, tinoxide, zirconium oxide, and radiopaque glasses that contain lanthanideor actinide compounds, tantalum, barium or strontium can be blended withthe dentalcrete powdered particulate to make the material more opaque tox-rays as discussed further below.

The particulate material must contain particles of suitable size. Tocreate a fine-powdered material, the particulate can be subjected toconventional air and solid media attrition techniques. This increasesthe surface area of the particles and reduces the particle size. Thepowdered particulate used in the composition of this inventionpreferably has a surface area of equal to or greater than 0.5 m²/g andmore preferably greater than 0.9 m²/g. The particles generally have asurface area in the range of 0.5 to 3.0 m²/g and more preferably 0.9 to3.0 m²/g. In one preferred embodiment, the particle size of the powderis reduced so that the maximum and average diameter sizes of theindividual particles fall below 40 μm, more preferably below 15 μm, andmost preferably below 10 μm. In some instances, the particles may be sofine that they have an average particle size of less than 1 μm. Theaverage particle size of the particulate is preferably in the range of10 times smaller than conventional portland cement particulate.Industrial and construction grade cement contain particles having anaverage particle size that is too large for the compositions of thisinvention. There also tends to be substantial agglomeration andaggregation of particles in such industrial cements. In contrast, thepowdered particulate used in the present formulation comprises discreteand individual particles, which are not substantially agglomerated oraggregated. These particles are characterized by having a small particlesize and large surface area. The small, discrete individual particles inthe composition provide several advantages over industrial cementparticles.

For example, using such fine particles means that the hydrauliccolloidal gel particles are more on a scale with dentinal tubules andlateral root canals in the tooth. The dentinal tubules in the root aremicroscopic, 1 to 3 μm in diameter, straight, and plentiful, with adensity of 800 to 57,000 per square millimeter. Secondly, the fineparticles can be blended easily and homogenously with the otheringredients of the composition. The small particles are mixed anddistributed uniformly within the resin matrix. In contrast, theparticles used in some traditional dental cements, for example, thecements described in the above-mentioned Kawahara et al., U.S. Pat. No.4,647,600, must first be surface-treated with inorganic or organic acidsbefore they are mixed with other components.

Using a powder particulate having such a small particle sizesignificantly improves the viscosity and handling properties of theultimate composition as discussed further below. The preferred powdercomprises particulate selected from dicalcium silicate, tricalciumsilicate, tricalcium aluminate, tetracalcium aluminoferrite, calciumphosphate, calcium sulfate dihydrate, silica, alumina, calcium oxide,and calcium hydroxide, and combinations thereof. The powder may containdifferent amounts of the calcium phases such as the following compounds(listed from most to least amount of calcium phases): tricalciumaluminate, dicalcium silicate, tricalcium silicate, tetracalciumaluminoferrite, calcium hydroxide, and calcium sulfate dihydrate.

The above-described particulate (dentalcrete) can be mixed with otherparticulate powders in accordance with this invention. In suchinstances, the particle size of each of the powdered materials should besubstantially equal. All of the particles dispersed in the resin matrixshould have substantially the same fineness. For example, in onepreferred version, the particulate is mixed with hydroxyapatite to formphoscrete as discussed further below. In another preferred embodiment,the particulate is mixed with a finely ground radiopaque material suchas bismuth oxide, tin oxide, tantalum oxide, zirconium oxide, bariumsulfate, barium or strontium-containing glasses, or other high atomicnumber, non-toxic, metal compounds including the lanthanides andactinides. Using such radiopaque materials, which absorb x-rayradiation, makes the composition visible in dental x-rays. Thecomposition, which replaces the removed tooth structure, is made visiblein the x-ray images. This helps the clinician confirm that thecomposition has been correctly placed in the teeth after thepulp-capping, pulpotomy, non-surgical, or surgical root procedure.

To form a phoscrete mixture, hydroxyapatite, a calcium phosphatecompound, is added to the mixture of calcium compounds in thedentalcrete. In general, autogenous bone has two basic components,organic and inorganic. The inorganic component of autogenous bone isprimarily hydroxyapatite, and the organic component is primarilycollagen. Hydroxyapatite powder is believed to help promote healing andrepair of the bone and tissue surrounding the root tip, or in contactwith dental pulpal tissue. Hydroxyapatite is compatible with the calciumcompounds of dentalcrete and provides a stable, non-resorbable platformfor bone and tissue repair. In the hydroxyapatite-containing dentalcretecomposition of the present invention, the hydroxyapatite component hasthe same mineral composition as human bone, thereby providing a naturalscaffold for bone and tissue regeneration. However, variations in thehydroxyapatite composition are equally suitable where the apatite ispartially replaced by carbonate, or the hydroxyl is partially replacedby fluoride. Also, compositional variations with the calcium beingpartially replaced by strontium or barium are also in the spirit of thesame invention. All of the compositions of this invention have gooddimensional stability and will not cause expansion and stress on teeth,nor shrink to allow bacterial transit.

Part B of the product is a liquid carrier comprising water-solublepolymers, and surfactants, and water. By the term, “water-solublepolymer” as used herein, it is meant any substance of high molecularweight that swells or dissolves in water. The water-soluble polymershould be non-toxic and compatible with other components of thecomposition. Examples of suitable water-soluble polymers include, butare not limited to, non-ionic polymers such as, for example, polyvinylalcohols (PVA) and its co-polymers, partially hydrolyzed polyvinylacetates, (PVAc), polyvinyl-pyrrolidone (PVP), hydroxyethyl methacrylate(HEMA), water-soluble poly-saccharides (e.g. xanthan gum), polyethyleneglycols and its water-soluble derivatives, polypropylene glycols and itswater-soluble derivatives. Various water-soluble co-polymers containingthe above residues also can be used. Additional examples ofwater-soluble polymers include anionic polymers such as, for example,polyacrylic acid (PAA), its water-soluble salts, derivative andcopolymers, polymethacrylic acid (PMA) its water-soluble salts,derivatives and its water-soluble copolymers, water-soluble copolymerscontaining maleic acid residues, poly-glucuronic acid, poly-glutamicacid its water-soluble salts, poly-aspertic acid and its water-solublesalts, hyaluronic acid and its water-soluble salts and derivatives,polystyrene sulfonates its salts and their copolymers.

In a preferred embodiment, the water-soluble polymer is selected fromthe group consisting of polyvinyl alcohols, polyvinyl-pyrrolidone (PVP),partially hydrolyzed polyvinyl acetates, (PVAc), polyacrylic acid (PAA),and polymethacrylic acid (PMA), and mixtures thereof. Preferably, themolecular weight of the water-soluble polymer is in the range of 20,000to 2,000,000. More preferably, the molecular weight of the water-solublepolymer is in the range of 80,000 to 2,000,000. Preferably, theconcentration of water-soluble polymer is in the range of about 5% toabout 40% by weight based on weight of the composition.

The surfactants used in the composition should be medically acceptableand suitable for use in dental applications. Adding the surfactantsimproves stability and handling properties. The surfactants interactwith the water-soluble polymers to form complexes that impart desirablerheological and other physical properties to the composition.Particularly, the resulting composition has a more “elastic” and“string-like” consistency when mixed with a powder. Importantly, theinteraction of the surfactants with the water-soluble polymers helpsimprove the elasticity of the composition when mixed with the powder.This means that the composition can be used like other resinous rootcanal materials. Furthermore, due to accelerated setting by thepolymers, the mixed material will not wash away easily from thelocalized treatment area. Examples of suitable surfactants include, butare not limited to, alkyl sulfates (for example, sodium dodecyl sulfate(SDS)), fatty acid salts with C₁₀-C₂₄ side chains, (for example, sodiumstearate), alkyl ether sulfates, alkyl sarcosinates, alkyl betaines, andother anionic, cationic, and non-ionic surfactants having alkyl sidechains suitable for human use. In a preferred embodiment, the surfactantis selected from the group consisting of alkyl sulfates, alkyl ethersulfates, and sarcosinates, and mixtures thereof. Preferably, theconcentration of surfactant is in the range of about 1% to about 40% byweight based on weight of the composition. The ratio of surfactant topolymer should be no greater than 6 to 1. In one preferred embodiment,the ratio of surfactant to polymer in the composition is 3:1 or less,and more preferably 0.5:1.

Various additives such as, for example, plasticizers, softening agents,humectants, stabilizers, and anti-bacterial agents also can be added tothe mixture. However, as opposed to some traditional cement materials,which require the addition of a calcium-type powder hardening agent suchas calcium hydroxide, there is no need to add such hardeners to thecomposition of this invention. Calcium hydroxide particulate optionallycan be added to the instant formulation, but it is not required. Rather,the formulation, by and in itself as described herein, has sufficientstrength and other desirable properties. Of course, it should beunderstood that calcium hydroxide may form as a reaction product whenthe powdered particulate is mixed and reacted with the liquid carrier.For example, the powdered particulate may contain particles oftricalcium silicate, dicalcium silicate, and tricalcium aluminatehydrate. When these compounds react with water, they produce severalreaction products including calcium hydroxide.

In practice, clinicians can dispense the powdered material (Part A) ontoa pad; add the liquid carrier (Part B); and mix the components togetherusing a spatula to form the composition of this invention. Theconcentration of powder particulate in the composition is generally inthe range of about 1 to about 80 weight percent, and the concentrationof liquid carrier is generally in the range of about 1 to about 50weight percent. To prepare a surgical or repair composition theparticulate powder is preferably mixed with the liquid carrier in aratio of three (3) to one (1). That is, in one preferred embodiment, thecomposition contains about 75 weight percent particulate and 25 weightpercent liquid carrier. In other instances, the particulate powder canbe mixed with the liquid carrier in different ratios such as, forexample, four (4) to one (1) or five (5) to one (1). If the compositionis intended to be used as a root canal sealer, the powder and liquid arepreferably mixed in a ratio in the range of 1:1 to 2.5:1. In the finalcomposition, the water content is generally in the range of about 1 toabout 50 weight percent, preferably 15 to 30 and the water-solublepolymer is generally present in an amount of about 1 to about 50 weightpercent, preferably 5 to 40 weight percent. If hydroxyapatite ispresent, it is preferably in a concentration of about 1 to about 30weight percent. If a radiopaque component is present, it is preferablyin a concentration of about 1 to about 60 weight percent.

Upon mixing the particulate powder with the liquid carrier, theparticles, which are hydrophilic, react with the liquid to formhydrates. For example, the particulate powder preferably containsparticles of tricalcium silicate, dicalcium silicate, and tricalciumaluminate. When these compounds react with water, they producetricalcium silicate hydrate, dicalcium silicate hydrate, calciumhydroxide, and tricalcium aluminate hydrate. Each mineral compoundreacts at a different rate. For example, the tricalcium silicate reactsrelatively quickly, while dicalcium silicate hydrates more slowly. Thematerial produced from the hydration reaction is a colloidal hydrategel. Preferably, the particles dispersed in the gel have a very smallparticle size as discussed above. The product begins to harden and willeventually solidify to form a material having high compressive strengthwhere the particles are mostly hydrated. Because the mixed material hasgood resistance to washout and displacement, the particulate materialcan react with the water and form a mass of relatively high compressivestrength (>30 MPa) in situ. The material is able to resist washing outwhen the root canal system is rinsed with water, or other fluid tocomplete a surgical procedure.

The surfactants interact with the water-soluble polymers to formcomplexes. As the surfactants interact with the polymer, the rheologyand other physical properties of the polymers change. In turn, thecomposition develops favorable properties; particularly, the handlingand placement properties of the composition are enhanced. The dentalclinician can work with and handle the hydrated gel more efficientlybefore it sets to form a rock-like substance in the root canal.Particularly, the composition has suitable rheological properties (forexample, viscosity, setting time, elasticity, consistency, and the like)so it can be effectively used for treating vital and non-vital teeth.Good elasticity is very important for root canal sealers. Thecomposition has good stability and holds the particulate in place, whichis very important for surgical procedures. In general, the combinationsof powder and liquid carrier compositions have either a putty-like orsyrup-like consistency as discussed further below.

It should be understood that mixing the powdered material with a liquidcarrier (containing water-soluble polymer, surfactant, and water) asdescribed above is but only one possible method of preparing thecomposition of this invention. Other methods can be used. For example,Part A can be prepared by blending the powdered particulate with thesurfactant and Part B can be prepared by dissolving the polymer inwater. Then, Parts A and B can be combined to form the composition thatwill be used in dental therapy. Another technique involves mixing thepowdered particulate with water (Part A) and then combining this mixturewith a previously prepared mixture of water-soluble polymer andsurfactant (Part B).

In some root canal treatment cases, gutta-percha and root canal sealermaterials can be extruded beyond the apex of a tooth. These materialscan be irritants and cause residual discomfort until the body resorbs orencapsulates the material over a period of months or years. Thecompositions of this invention have good biocompatibility with the rootcanal system and promote normal healing of the bone and tissuesurrounding the root tip, particularly if any of the material isextruded beyond the apex. The composition enhances the growth of newbone and tissue surrounding the root tip if an infection was present andis anti-microbial when it makes contact with bacteria. Adding thebioactive hydroxyapatite powder further enhances these phenomena topromote growth of cementum or reparative dentin, depending upon theapplication of the material.

The improved compositions of this invention provide enhanced bonding togutta-percha and to dentin. Bonding of sealer to dentin or gutta-perchahas been a topic of great concern to endodontists in the prevention ofbacterial migration in obturated, root-canal-treated teeth. Thehydrophilic nature of the calcium silicate and calcium aluminatecompounds enhances the reactivity of the composition of the presentinvention with moist dentin. In addition, the formulations of thepresent invention have enhanced bonding to gutta-percha, owing to thepresence of the hydrophobic side chains in the partially hydrolyzedpolyvinyl acetate and/or other polymers used. The hydrophobicside-chains have an affinity for gutta-percha. Because of their improvedbonding properties, the composition provides an improved barrier tobacterial and fluid leakage in the root canal system of a tooth. Thecomposition effectively seal offs communication pathways from thecoronal to the apical portions when used as a root canal sealer,obturation material, root-end filling, apexification, perforationrepair, or root resorption. As a result, bacterial migration into theroot canal system is reduced or prevented.

The improved compositions of this invention can be either putty-like orsyrupy in viscosity. When the composition is in the form of a putty-likematerial, it can be used in root canal indications such asapicoectomies, apexification, perforation repair, obturation,pulpotomies, or root-resorption repair. When the composition is in theform of an elastic material having a honey-like consistency, it can beused for root canal sealing or perhaps obturation. The rheologicalproperties (viscosity, elasticity, and the like) of the powder-liquidcombination are determined by the particle size distribution of thepowder, the composition of the liquid, and the powder to liquid ratio.Finer powders; more viscous liquids; more polymers; and a higher powderto liquid ratio all make a more putty-like material used forpulp-capping, cavity liner, root-end filling, obturation, pulpotomies,apexification, or treating perforations or root resorption. Thecomposition of this invention is introduced into the tooth from thecoronal or apical openings.

For example, the compositions can be used to seal at least a portion ofthe tooth; repair root perforations; repair root resorption; fill rootends; and cap at least a portion of the dental pulp that has beenexposed. The composition also can be used to line a cavity preparationwhere pulp-exposure is possible. Moreover, complete obturation of rootcanals can be performed using the material of this invention. Inaddition, after a pulpotomy has been performed, the composition can beused to cover a root access opening in a root. In yet another example,the composition can be used to seal a root canal after gutta-percha hasbeen introduced into the canal.

The invention is further illustrated by the compositions described inthe following Examples, but these Examples should not be construed aslimiting the scope of the invention.

EXAMPLES Example A

A root canal sealer was formulated with dentalcrete having 40 wt. %bismuth oxide and 60 wt. % of a mixture of calcium silicates, calciumaluminate, and calcium sulfate. (The approximate composition was 73 wt.% tricalcium silicate, 17 wt. % dicalcium silicate, 5 wt. % tricalciumaluminate, 1 wt. % tetracalcium ferrite, and 4 wt. % calcium sulfate.)The liquid carrier mixed with this powder contained 5 wt. % partiallyhydrolyzed polyvinyl acetate, 15 wt. % sodium n-dodceyl sulfate and 80wt. % water. The resulting root canal sealer formulation is identifiedas “Experimental MTA’ in this Example A and in FIG. 1.

The microleakage (hydraulic conductance) of root canal systems (humanteeth) sealed with Experimental MTA was tested in vitro. Cleaning andshaping of the teeth as well as canal obturation were performed under anoperating microscope (OPMI pico, Carl Zeiss Surgical, Inc., Thornwood,N.Y.). Detailed radiographic documentation of the pre-operativespecimens, working lengths, cone-fit, post-operative condition of theroot fillings. For each root segment, canal patency was achieved usingISO size #15 Flex-o-file (Dentsply Tulsa Dental Specialties). Theworking length was established at 1 mm short of the apex. Cleaning andshaping of the root canals was performed with a crown-down technique,using size 2-4 Gates Glidden drills and Profile nickel-titanium rotaryinstruments (Dentsply Tulsa Dental Specialties). All canals wereprepared to ISO size 40, 0.06 taper. To ensure optimal cutting efficacy,a new set of rotary instruments was used for the shaping of two roots.

Experimental Group—

Ten teeth were randomly selected for the experimental group. Canals wereirrigated between instrumentation with 5 mL of 1.3% sodium hypochlorite(NaOCl) delivered to within 2 mm of the working length using BioPure™MTAD irrigation needles (ProRinse Needles; Dentsply Tulsa DentalSpecialties). For each root canal, 5 mL of BioPure MTAD root canalcleanser solution (Dentsply Tulsa Dental Specialties) was used for 5 minafter the completion of instrumentation and as the final rinse prior toroot canal obturation, according to the manufacturer's instructions. Thedebrided root canals were dried with multiple paper points (LexiconAP0640, Dentsply Tulsa Dental Specialties). A size #40 Lexicon 0.06taper gutta-percha master cone (Dentsply Tulsa Dental Specialties) wastried-in to within 1 mm of the working length, with additional trimmingif necessary to achieve tug-back. Cone-fitting was confirmedradiographically prior to root canal obturation. The experimental rootcanal sealer composition of this invention was freshly mixed for eachroot canal obturation by mixing the powder and the liquid uniformly intoa homogenous mix at a ratio of 2:1 powder to liquid. The mixedexperimental root canal sealer was introduced into the root canal withthe master gutta-percha cone and spread as evenly as possible along theroot canal walls.

Control Group—

Ten teeth were randomly selected for the control group. Each canal wasirrigated between instrumentation with 5 mL of 2.6% sodium hypochlorite(NaOCl) delivered to within 2 mm of the working length using theProRinse irrigation needles (Dentsply Tulsa Dental Specialties). Five mLof 17% (0.5M; pH=7.4) ethylenediamine tetra-acetic acid (EDTA) were usedfor 1 min after the completion of instrumentation and as the final rinseprior to root canal obturation. The debrided root canals were dried withmultiple paper points (Lexicon AP0640, Dentsply Tulsa DentalSpecialties). As with the experimental group, a size #40 Lexicon 0.06taper gutta-percha master cone (Dentsply Tulsa Dental Specialties) wastried-in to within 1 mm of the working length, with additional trimmingif necessary to achieve tug-back. Cone-fitting was also confirmedradiographically prior to root canal obturation.

A comparative Pulp Canal Sealer (zinc oxide eugenol sealer having apowder base and liquid catalyst), available from Kerr Corp. (Orange,Calif.) was mixed according to the manufacturer's instructions andintroduced into the root canals of the control group teeth with mastergutta-percha cones.

Control & Experimental: The root canals were similarly obturated withthe continuous wave condensation technique using the System B heatsource at 200° C. and then backfilled with the Calamus Flow ObturationDelivery System (Dentsply Tulsa Dental Specialties) using the 23 gaugeCalamus™ Flow Singles gutta-percha cartridges.

Testing—

The filled specimens from both the experimental and the control groupswere stored for seven days at 37° C. and 100% relative humidity to allowthe sealers to set. Leakage of the filled roots in each group (N=10) wasevaluated using a modified fluid filtration study design that representsa modification of the previously reported protocol by Pashley and Depew.(Pashley D H, Depew D D. Effects of the Smear Layer, Copalite andOxalate on Microleakage, Oper Dent 1986; 11:95-102.)

Briefly, a Plexiglas connection platform was first constructed byinserting a short length of an 18-gauge stainless steel tubing into acenter hole created in a 2×2×0.6 cm piece of Plexiglas. The tubingprotruded 1 mm from the top of the Plexiglas. A 2 mm deep cavity wasthen created from the coronal end of each root segment using a slowspeed tungsten carbide bur. This modified technique created a reservoirfor the insertion of the protruded metal tubing. The rationale for thismodified protocol is based on the results obtained from a recentlyconducted pilot study that this technique eliminated clogging of themetal tubing and prevented the generation of false negative results. Thetooth segment was attached to the Plexiglas platform and sealed with acyanoacrylate adhesive, (Zapit, Dental Ventures of America, Inc.,Anaheim Hills, Calif.). Each filled root was cemented with Zapit to thePlexiglas platform so that the coronal root canal orifice was centeredover the orifice of the metal tubing. A radiograph was then taken of theattachment of the root segment to the fluid filtration device to ensurethat the metal tubing was corrected inserted into the reservoir createdalong the coronal part of the root segment.

To measure microleakage, each Plexiglas-root assembly was attached to afluid filtration apparatus as described previously by Derkson et al. andmodified by Wu et al. (Wu M K, de Gee A J, Wesselink P R, Moorer W R.Fluid Transport and Bacterial Penetration Along Root Canal Fillings, IntEndod J 1993; 26:203-8. Polyethylene tubing (Fisher Scientific,Pittsburgh, Pa.) was used to connect the pressure reservoir to a 25 μLmicropipette (Microcaps, Fisher Scientific). Additional tubing was usedto connect the micropipette to a micro syringe (Gilmont instruments,Inc., Great Lakes, N.Y.) and the Plexiglas with the attached root. Asmall (1 to 2 μL) air bubble was subsequently introduced into the systemwith the micro-syringe and advanced into the micropipette. A pressure of69 kPa (i.e. 10 psi) was then applied via the use of nitrogen gas to aphosphate buffer containing reservoir inside a modified pressure cooker.The phosphate buffer was forced through the voids along the root canalfilling, displacing the air bubble in the micropipette. Quantificationof the fluid flow per unit time was performed by observing the movementof the air bubble in the micropipette. Linear movement of the air bubblein millimeters was recorded after 10 min of equilibration of the fluidfiltration system to enable complete relaxation of the stretchedpolyethylene tubing. Linear fluid movement within the micropipette wasconducted for a period of 15 min and expressed as mm/min. Three of these15-min measurements were performed for each root segment, from which themean linear fluid movement was derived. The mean fluid flow rate of eachroot segment was calculated by multiplying the mean linear fluidmovement by the internal bore diameter of the micropipette (0.386 mm²)and expressed as μL min⁻¹ 69 kPa⁻¹.

Determination of Fluid Flow Rate for the Positive and Negative Controls

The protocol described above was employed for the determination of thefluid flow rates in the negative control group and the second positivecontrol group. For the first positive control group (i.e. unfilled rootcanals), a modification of the protocol was necessary as the extremelyrapid fluid movement did not permit the recording of linear fluidmovement by following the bubble within the micropipette. Accordingly, apre-weighed plastic beaker was placed over the apex of the root segmentin this group, after the latter was connected to the fluid filtrationapparatus. The phosphate buffer that was expressed through the root apexwas collected in the plastic beaker. The time for the recording was alsoreduced from 10 min to 1 min. The weight of the water that was collectedduring the one minute period at 69 kPa pressure was converted intovolume (mL). The flow rates in the first positive control group weresimilarly expressed as μL min⁻¹ 69 kPa⁻¹.

Data Treatment and Statistical Analysis

The 10 psi pressure was converted into cm water pressure (705 cm) andthe mean fluid flow rates (i.e. hydraulic conductance) in all groupswere expressed in μLmin⁻¹cmH₂O⁻¹. The hydraulic conductance data fromthe experimental group and the control group were statisticallyanalyzed.

A summary graph is provided in FIG. 1. As shown, the microleakage of theexperimental MTA sealer with gutta-percha was not statisticallydifferent from the control (master cone of gutta-percha with Kerr's PulpCanal Sealer). However, when an outlying data point from each group wasremoved, the hydraulic conductance of the control material was muchgreater at 28 days than the new root canal sealer composition of thisinvention. The composition of this invention (Experimental MTA) is thusmore effective in sealing the root canal. The composition is capable offorming a barrier that resists fluid permeation into the canal. Thecomposition can seal off fluid pathways between the root canal systemand surrounding tissue.

Example B

The powdered particulate material described in Example A was used withvarious liquid carriers to prepare the compositions in this Example B.Particularly, the powder was mixed with the liquids listed in thefollowing Table 1 to prepare various compositions. The concentration ofpowder in the composition was in the range of about 67 to about 80% byweight. When the powder was mixed with about 20% liquid, a putty-likecomposition was obtained. This composition could be used for root canalobturation, root-end repair, perforation repair, or other procedures.The sodium n-dodecyl sulfate improved the handling, but didn'taccelerate the setting. The polyvinyl acetate may inhibit the settingwhen used alone. The combination of PVA with SDS, created the elasticitydesired for some dental uses. The resulting mixtures were resistant towashout with a stream of water and hardened quickly enough to allow aclinician to proceed with covering the site and finishing the procedure.Various viscosities were obtained, but it is believed that each of theprepared compositions would be satisfactory for use in root canalobturation, root-endroot-end repair, and perforation repair. When about33% liquid was added, an elastic consistency was obtained, and thecomposition was suitable for use as a root canal sealer material.

Surprisingly the combination of polyvinyl alcohol or hydrolyzedpolyvinyl acetates and sodium n-dodecyl sulfate had synergistic effects;when a liquid carrier containing these ingredients was mixed with thepowders, the resulting composition had an elastic consistency thatallowed the material to be used as a root canal sealer. This combinationof water-soluble polymers also reduced the apparent setting time andincreased the washout resistance of the powder/liquid mixture.Separately, neither polymer in water was as satisfactory. Variouspolyvinyl alcohols were tested and all made a suitable mixture of variedviscosity. The partially hydrolyzed polyvinyl acetate was as viable asthe fully hydrolyzed polyvinyl alcohol. The best liquid carriercombination was that of Sample 4 where the ratio of surfactant towater-soluble polymer was 6 to 1.

Example B

TABLE 1 Liquid Carriers 1-24 (Concentration of Components by Weight %)Component 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Water 95 89.3 90 82.5 87.5 92.5 88 81 80 78 65 75 65 95 92.5 90 93 90 9080 70 80 60 70 Polyvinyl 4 7.1 2.5 2.5 2.5 2 acetate 100% hydrolyzed87,000 to 97,000 ave mole wt. Polyvinyl 4 5 7 5 5 5 5 7.5 10 acetate 87to 89% hydrolyzed; 87,000 to 97,000 ave mole wt. Polyvinyl 5 10 10 20 30acetate 75% hydrolyzed; <80,000 mole wt. Sodium n- 1 3.6 10 15 10 5 1015 15 15 30 20 30 20 40 30 dodecyl sulfate Chlorhexidine 2 gluconate

Example C

In this Example C, the powdered particulate material described inExample A was used, and different liquid carriers were tested as shownin Table 2. The concentration of powder in the composition was in therange of about 67 to about 75% by weight. The viscosities varied amongthese samples, but each sample was satisfactory for dental applications.The Steol material was a suitable substitute for the sodium n-dodecylsulfate. Polyvinyl pyrrolidone was also a suitable material to useinstead of polyvinyl acetate. However, when used alone, the polyvinylpyrrolidone did not create an elastic mixture, although the setting wasaccelerated and seemed to add early strength to the mixtures.

Example C

TABLE 2 Liquid Carriers 1-4 (Concentration of Components by Weight %)Component 1 2 3 4 5 6 7 8 9 Water 92.5 92 91.5 89 96 92 90 81.7 83 SteolCA-460 5 5 5 4 Ammonium laureth sulfate Polyvinyl acetate 87 2.5 3 3.5 7to 89% hydrolyzed Sodium n-dodecyl 10 5 sulfate Polyvinyl pyrrolidone 48 10 8.3 10

Example D

The powdered particulate material described in Example A was used toprepare the compositions in this Example D. Different liquid carrierscontaining the organic components listed in Table 3 were tested. Theconcentration of powder in the composition was in the range of about 67to about 75% by weight. These liquids enabled the powder to set, butwere less resistant to washout when mixed with dentalcrete by a streamof water than those liquids in Examples A, B, and C.

Example D

TABLE 3 Liquid Carriers 1-9 (Concentration of Components by Weight %)Component 1 2 3 4 5 6 7 8 9 Water 88 96 90 82 95 96.5 90 88 78 Sodiumpolyacrylate (low 5 10 5 3.5 5 5 10 molecular weight) Sodiumpolyacrylate (high 2 molecular weight) Polyvinyl acetate 87 to 5 5 2 489% hydrolyzed, average molecular weight 88,000 to 97,000 Sodiumn-dodecyl sulfate 10 5 5 8 Chlorhexidine gluconate 2 2 2 Polyvinylacetate 1

Example E

In this Example E, the powdered particulate material described inExample A was used. Different liquid carriers containing the organiccomponents listed in Table 4 were tested. The concentration of powder inthe composition was in the range of about 67 to about 75% by weight. Thecomponents included polyvinyl pyrrolidone and glycerol. These glycerolcompounds retarded the setting of the powder so much that the materialscould not be used appropriately.

Example E

TABLE 4 Liquid Carriers 1-9 (Concentration of Components by Weight %)Component 1 2 3 4 5 6 7 8 9 Water 57.5 60 48 43.7 57.5 80 20 50 84Polyvinyl pyrrolidone, 7 molecular weight 1,300,000 Polyvinyl acetate 87to 5 6.3 2.5 6 89% hydrolyzed, average molecular weight 88,000 to 97,000Sodium n-dodecyl sulfate 10 10 28 12.5 3 Chlorhexidine gluconate 2 10Cocoamidopropyldimethyl 0.5 betaine Glycerol 25 30 24 37.5 30 20 80 50

Composition 9 in above Table 4, which did not contain glycerol, wastested for its microleakage and found to be equal to or superior toconventional materials used for root-end fillings during endodonticsurgery. This composition is referred to as “Phoscrete” in this ExampleE and in FIG. 2. Leakage was compared with two commercially—available,frequently advocated root-end filling materials, White ProRoot MTA(Dentsply Tulsa Dental Specialties) and Super EBA (Bosworth Company,Skokie, Ill.).

In the test procedure, cleaned and shaped single-rooted teeth werefilled with single gutta-percha cones without sealers, and severed attheir root ends. Forty-two recently extracted human single-rooted teethwere stored until use in 0.9% NaCl solution containing 0.02% sodiumazide to prevent bacterial growth. Instrumentation was performed with acrown-down technique using ProTaper nickel-titanium rotary instruments(Dentsply Tulsa Dental Specialties) until 1 mm of a F3 ProTaper file tipextruded beyond the apical foramen. The canals were rinsed with 10 mL of6.15% sodium hypochlorite in between instrumentation followed by the useof 5 mL of 17% ethylenediamine tetraacetic acid as the final rinse. Theapical 3 mm of each instrumented root was resected with a 10 degreebevel to its longitudinal axis. Root end preparations were made to adepth of 3 mm using ultrasonic tips.

The mixed materials were compacted into the root end preparations usingmicrosurgical pluggers and the filled teeth were placed inside a humidorat 37° C. and 100% relative humidity for 24 hours and then stored in aseparate scintillation vial containing 10 mL of phosphate-bufferedsaline. The teeth were aged in phosphate-buffered saline. Leakage wasevaluated at 3 and 42 days. Leakage of the root-end fillings wasevaluated using a fluid filtration design. Quantification of the fluidflow (μL/min) was performed by monitoring the displacement of a waterbubble inside the glass capillary tube of a Flodec device via alight-sensitive photodiode. Data collection was performed every 1.04 secusing the Flodec software and the results are shown in FIG. 2. For the3-day testing period, differences between materials that have the sameupper case letter designations (e.g., B and B) are not statisticallysignificant (p>0.05). For the 42-day testing period, differences betweenmaterials that have the same lower case letter designations (e.g., b andb) are not statistically significant (p>0.05). For each root-end fillingmaterial, before and after subgroups that are linked by a blackhorizontal bar indicate significant differences in fluid leakage(p<0.05).

For both testing periods, leakage in the Super EBA group wassignificantly higher than the other two groups (White ProRoot MTA andPhoscrete experimental sealer of this invention in FIG. 2), which werenot different from each other. For each material, leakage at 42 days wassignificantly lower than the leakage at 3 days. The experimentalroot-end filling Phoscrete material created an excellent seal.

Example F

The powdered particulate material described in Example A was used inthis Example F. The concentration of powder in the composition was inthe range of about 67 to about 75% by weight. Different liquid carrierscontaining different organic components as listed in Table 5 including:polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl acetate, and sodiumn-dodecyl sulfate were tested. These liquids enabled the powder to set,and were very resistant to washout by a stream of water. Surprisingly,the combinations were more resistant to washout than any of thematerials tested individually.

Example F

TABLE 5 Liquid Carriers 1-9 (Concentration of Components by Weight %)Component 1 2 3 4 5 6 Water 80 82 83 84 83 82 Polyvinyl pyrrolidone, 7 77 7 7 7 molecular weight 1,300,000 Polyvinyl acetate 87 to 10 8 7 6 6 689% hydrolyzed, average molecular weight 88,000 to 97,000 Sodiumn-dodecyl sulfate 3 3 3 3 3 3 Chlorhexidine gluconate 1 2

The liquid carriers having the components described in Table 5 appear tobe the most preferred liquids for mixing with the particulate powders tomake the compositions of this invention. It has been found that theconcentration of components in the liquids can be adjusted as shown, forexample, in Table 5, and the resulting compositions are suitable for usein various endodontic indications. These applications include, forexample, root canal sealing, root canal obturation, root repairs, andvital pulp therapy.

Example G

In this Example G, different powdered particulate materials wereprepared and tested. The Example G powders differed from the powderdescribed in Example A by the addition of different polymers. Water wasadded to the Example G powders. The below Table 6 describes thecomponents in more detail. It was found that the resulting compositionsof Example G had inferior handling and setting properties as compared tothe compositions of Example F.

Example G

TABLE 6 Compositions 1-5 (Concentration of Components by Weight %)Component 1 2 3 4 5 Dentalcrete 97 92 98 92 86 Sodium n-dodecyl sulfate3 8 Sodium polyacrylate 1 7 7 Xanthan gum 1 1 7

Example H

In this Example H, the powder component was modified to includehydroxyapatite or calcium sulfate. The liquid carriers of Example F wereused with the powder. In particular, the liquids were mixed with thepowder in a powder to liquid ratio of 4 to 1 (80% powder). Thecombination of Liquid Carrier No. 4 (Example F) with Powder Mixture No.1 in Table 7 below was a preferred composition in this Example. Theconsistency of the composition was putty-like. The radiopacity of thecomposition was equal to 9 to 10 mm of aluminum, measured per the methodin ISO 6876.

Example H

TABLE 7 Particulate Powders 1-3 (Concentration of Components by Weight%) Component 1 2 3 Calcium silicate & calcium aluminates 56 56 59Bismuth oxide 36 36 36 Calcium sulfate 10 5 Hydroxyapatite 10

Example I

In this Example I, the powder component described in Example A was used.The liquids described in Table 8 below were mixed with the powder. Thesilica sol improved the handling of the composition, but did not speedthe setting. The potassium carbonate accelerated the setting of thecompositions, but the washout-resistance of the composition was not asstrong as desired. Rinsing is used in dentistry to clean a surgical siteor an area of blood before a site is closed. This is usually done withsterile water or sterile solution. Thus, it is important that thecompositions have good washout-resistance so that it will not rinseaway.

TABLE 8 Liquids Carriers 1-3 (Concentration of Components by Weight %)Component 1 2 3 Water 97.5 98 80 HEMA Potassium Carbonate 2.5 2 SilicaSol 20

Example I Example J

In this Example J, various organic components, as described in Table 9,were added to the powdered particulate (described in Example A) andmixed with water to prepare the compositions.

Example J

TABLE 9 Compositions 1-9 (Concentration of Components by Weight %)Component 1 2 3 4 5 6 7 8 9 Water 23 30 25.1 23 24 26 Dentalcrete powder70 63 67.4 69 75 82 82 73 69 Citric acid 6 Phosphorylcholine 7 compoundPotassium poly vinyl 7.5 sulfate Sodium polyacrylate 8 2 Polyacrylicacid 25 Dilute polyacrylic acid 18 Methacrylic acid (25%) 18 Polystyrenesulfonate 4 2 sodium salt

These compositions accelerated the setting of the powders compared tocompositions containing just water, but did not have thewashout-resistance that the liquids in Example F conferred.

Example K

In this Example K, the endodontic biocompatibility of a material madeaccording to the present invention (composition No. 1 in Example H mixedwith liquid carrier No. 4 in Example F in a powder to liquid ratio of4:1) and commercially-available White ProRoot MTA Sealer/water weretested. Four dogs were the subjects of this protocol for root canaltreatment. The four maxillary anterior teeth, the maxillary 2^(nd) and3^(rd) premolars, and the mandibular 2^(nd) 3^(rd), and 4^(th) premolarswere used in the experimental design. Pre-operative and post-operativeradiographs of the maxillary anterior teeth and the mandibular premolarswere taken using the XCP radiographic system or with Occlusal intra-oralfilm. Pulpotomies were performed in the maxillary 2^(nd) and 3^(rd)premolars. Experimental or control materials were placed directly ontothe coronal pulp stumps. For the mandibular 2^(nd), 3^(rd) and 4^(th)premolars, furcal perforations were made in intentional, iatrogenictooth perforations following previously standardized protocols. Theperforations were repaired with the control or the experimentalmaterial. For the teeth that were treated for a root-end filling, rootcanal treatment was performed. All canals were obturated with materialto be used for the root-end filling. After completion of the root canalobturation, the surgical procedures were performed.

At the end of 60 days, canine subjects were sacrificed. Block sectionsof the jaws containing the roots were cut and x-rayed. The blocksections were then processed for histological examination. The teethwere separated and oriented for histological sectioning, dehydrated, andembedded in paraffin blocks. Serial sections in a bucco-linguallongitudinal orientation of 5 to 7 microns thickness were prepared forlight microscopic examination using a Leitz 1512 rotary microtome.Sections were stained with Hematoxylin/Eosin (H&E). The root canaltissue responses were graded independently and blindly (that is, thematerial was not known) by one histologically skilledendodontist-investigator. The scores for each tooth section wererecorded and then averaged.

The experimental material in this test, was much improved over thecontrol material in its handling and setting. The new material was mucheasier to mix and place for all the procedures. Healing was significantas seen by radiographic evidence of bone growth post-treatment.

The following Tables 10 and 10A show the histological evaluationresults.

TABLE 10 Root Reactions of Sample Materials/Average Scores PeriapicalBone inflammation Cementum quality PDL Resorption Experimental 0.8 1.80.8 1.3 0.2 Control 0.5 3.0 1.5 1.5 0.0

TABLE 10A Pulpotomies Using Experimental Material/Average ScoresReactional Pulp tissue dentin Inflammation organization formationDentinogenesis Experimental 0.7 1.2 2.7 1.3

In the histological sections evaluated, the vast majority of the samplesexhibited no inflammation (average score less than 1—a score of zeroindicates normal healthy tissue that one would find with no treatment.)The quality of the bone regenerated adjacent to the surgical site andthe root tips was also normal in the majority of samples examined. Therewas significant layering of new bone that had invaginated into thesurgical sites, surrounded by new osteoblasts on it surface. Layering ofthe new inorganic matrix (future bone forming cells) was evident. Fewosteoclasts were seen, and no resorption of the material. Cementumdeposition was seen on the majority of the resected dentinal surfaces.The average score was 1.8 for ERTM1, indicating that close to 50% of theroot apertures were covered with varying layers of cementum covering theroot aperture, of various thicknesses and morphological characteristics.Apical periodontal ligament formation was normal in all cases.Functionally oriented collagen fibers surrounded the root ends in manysections. The majority of samples had these fibers inserted into the newcementum or bone that had formed during healing. The presence of rootsurface resorption was very limited (score=0.2 for experimentalmaterial). Where found, the resorption itself was not adjacent to theexperimental material. Some cellular destruction at the furcations wasseen, due to furcation exposure to the destructive oral environment.However, when protected from exposure, good healing was observed. Somefurcal perforation sites were lost during decoronation of the samples,where the furca can be very high in canine anatomy.

In the grading of the pulpotomy specimens the majority of casesexhibited minimal to no inflammation. A wide range of pulpalmorphologies were seen, ranging from normal tissue to somedisorganization of the odontoblastic layer, to total disorganization ofthe pulpal tissue morphology. However, even in cases in which there wastotal disorganization of the pulpal tissue, evidence was seen ofmoderate formation of hard tissue deposition beneath the experimentalmaterial. This hard tissue indicates that the pulpal disorganization mayhave been an artifact during specimen preparation. Few cases exhibitedhighly organized dentinogenesis at 60 days; however, the hard tissuebarriers that did form were dense and thick with some evidence of normaldentinogenesis at the lateral borders (tubular dentin formation).

The experimental material did contribute to repair of periradiculartissues, including the periodontium. A dentinal barrier was formed thatprotected the pulps in the traumatizing pulpotomy. No resorption of thematerial was seen.

In summary, the experimental material was biocompatible with theperiapical and pulpal tissues of these canine subjects after 60 days.The material was suitable for use in contact with these tissues toinduce healing and repair of tissues. All of the specific indicationstested were satisfactory both radiographically and histologically.

Handling

The composition of this invention has optimum handling. The calciumsilicates and aluminates, handle better when coarse particles areeliminated, and the water soluble substances noted herein are combined.The handling improvements make it significantly easier for a clinicianto use these hydraulic materials for dental procedures, placing them atthe point of disease or trauma.

Working and Setting Times

The composition of this invention has optimum working and setting times.Working time is measured according to Dental Standards ISO9917 or ISO6876 (water-based dental cements) and is the period of time measuredfrom the initial mixing of the ingredients to the point when thematerial begins to harden—the material can be manipulated during thistime with no adverse effect on the properties of the material. The netsetting time is also measured according to Dental Standards ISO-9917 andis the period of time measured from the end of mixing of the ingredientsto the point when the material sets. More particularly, the net settingtime is measured by casting the material in a mold. After the mixing hasbeen completed, the indenter device is vertically lowered onto thesurface of the cement and it is allowed to remain there for 5 seconds. Atrial run is carried out to determine the approximate setting time,repeating the indentations at 30 second intervals until the needle failsto make a complete circular indentation in the cement, when viewed using2× magnification. The needle is cleaned, if necessary, betweenindentations. The process is repeated, starting the indentation at 30seconds before the approximate setting time thus determined, makingindentations at 10 second intervals. The net setting time is recorded asthe time elapsed between the end of mixing and the time when the needlefails to make a complete circular indentation in the cement. A similartesting procedure, ISO 6876 (root canal sealers) can be used formeasuring the working and setting times of the composition.

In general, the compositions of this invention have a working time inthe range of about five (5) minutes to about sixty (60) minutes. Theexact working time period of the composition depends on its specificformulation. As discussed above, different formulations can be used forroot canal apicoectomies, apexification, perforation repair, obturation,pulpotomies, pulp-capping, cavity liners, root-end resorption repair,and root canal sealing. The final setting time is generally within therange of about ninety (90) minutes to about twelve (12) hours. Thisshortened working time allows the dental practitioner to handle andplace the material more effectively. The clinician can fill or repairthe root canal and see the material begin to harden and form a rock-likesubstance. The clinician is better able to work and shape the material.After the clinician applies the material to the targeted area, itremains in place. The material has good consistency and does not migrateaway from the area. This allows a clinician to clean-up a site byrinsing when a surgical or vital pulp therapy procedure is performed andblood is present. Furthermore, additional dental material, such as arestorative composite, can be placed over the root canal filling/sealingmaterial as it begins to set. Used for pulp-capping or cavity linerprocedures, the placed root canal filling/sealing material bonds to theroot dentin and, preferably, to any other materials (for example,gutta-percha or dental composite) being used to fill the root canal ortreat the vital pulp. As the root canal filling/sealing composition setsand hardens, it provides a solid barrier to bacterial and fluid leakagein the root canal system. The fluid pathways between the root canalsystem and surrounding tissue are tightly sealed off. Furthermore, theroot canal filling/sealing material is bactericidal.

Workers skilled in the art will appreciate that various modificationscan be made to the illustrated embodiments and description hereinwithout departing from the spirit and scope of the present invention. Itis intended that all such modifications within the spirit and scope ofthe present invention be covered by the appended claims.

What is claimed is:
 1. A dental composition comprising: a) about 1 toabout 80% by weight of particulate material including: (i) calciumsilicate, calcium aluminate, tetracalcium aluminoferrite, calciumphosphate, calcium sulfate, silica, alumina, calcium oxide, calciumhydroxide, or mixtures thereof; wherein the particulate material has anaverage particle size of less than 40 microns; and b) about 1 to about50% by weight liquid carrier including: (i) water-soluble polymer, and(ii) water.
 2. The composition of claim 1, wherein the water-solublepolymer is selected from the group consisting of polyvinyl alcohols,polyvinyl-pyrrolidone (PVP), partially hydrolyzed polyvinyl acetates,(PVAc), polyacrylic acid (PAA), and polymethacrylic acid (PMA),hyaluronic acid, water-soluble poly-saccharides, poly amino-acids, andcopolymers and mixtures thereof.
 3. The composition of claim 1, furthercomprising about 1 to about 30% by weight of hydroxyapatite.
 4. Thecomposition of claim 1, further comprising about 1 to about 60% byweight of a radiopaque component.
 5. The composition of claim 4, whereinthe radiopaque component is selected from the group consisting ofbismuth oxide, barium sulfate, tantalum oxide, cerium oxide, tin oxide,zirconium oxide compounds and radiopaque glasses containing tantalum,barium and strontium, and mixtures thereof.
 6. The composition of claim1, wherein the particulate material comprises a mixture of tricalciumsilicate and dicalcium silicate particles.
 7. The composition of claim1, wherein the particulate material comprises about 20 to about 80 wt. %tricalcium silicate; about 20 to about 50 wt. % dicalcium silicate;about 1 to about 20 wt. % tricalcium aluminate, about 1 to about 8 wt. %tetracalcium aluminoferrite; about 1 to about 15 wt. % calcium sulfatedihydrate, and about 1 to about 50 wt. % radiopaque component.
 8. Thecomposition of claim 7, wherein the particulate has an average particlesize in the range of about 1 μm to about 40 μm.
 9. The composition ofclaim 7, wherein the particulate material has an average particle sizein the range of about 1 μm to about 15 μm.
 10. The composition of claim1, further comprising anti-bacterial and/or anti-microbial agents. 11.The composition of claim 10, wherein the anti-microbial agent includeschlorhexidine gluconate.
 12. A method of treating a root canal in atooth, comprising the steps of: a) preparing the root canal in the toothto be treated, b) providing a composition comprising: (i) a mixture ofabout 1% to about 80% by weight of particulate material includingcalcium silicate, calcium aluminate, tetracalcium aluminoferrite,calcium phosphate, calcium sulfate, silica, alumina, calcium oxide,calcium hydroxide and mixtures thereof, wherein the mixture has anaverage particle size of less than 40 microns; and (ii) about 1% toabout 80% by weight of a liquid carrier including: (1) water-solublepolymer; and (2) water; and c) introducing the composition into thetooth from coronal or apical openings.
 13. The method of claim 12,wherein the water-soluble polymer is selected from the group consistingof polyvinyl alcohols, polyvinyl-pyrrolidone (PVP), partially hydrolyzedpolyvinyl acetates, (PVAc), polyacrylic acid (PAA), and polymethacrylicacid (PMA), hyaluronic acid, water-soluble poly-saccharides, polyamino-acids, and mixtures thereof.
 14. The method of claim 12, whereinthe composition further comprises a humectant.
 15. The method of claim12, wherein the composition further comprises about 1 to about 30% byweight of hydroxyapatite.
 16. The method of claim 12, wherein thecomposition further comprises about 1 to about 40% by weight of aradiopaque component.
 17. The method of claim 16, wherein the radiopaquecomponent is selected from the group consisting of bismuth oxide, bariumsulfate, tantalum oxide, cerium oxide, tin oxide, zirconium oxidecompounds and radiopaque glasses containing tantalum, barium andstrontium, and mixtures thereof.
 18. The method of claim 12, wherein theparticulate material comprises a mixture of tricalcium silicate anddicalcium silicate particles.
 19. The method of claim 12, wherein theparticulate material comprises about 20 to about 80 wt. % tricalciumsilicate; about 20 to about 50 wt. % dicalcium silicate; about 1 toabout 20 wt. % tricalcium aluminate, about 1 to about 20 wt. %tetracalcium aluminoferrite; about 1 to about 15 wt. % calcium sulfatedihydrate, and about 1 to about 50 wt. % radiopaque component andwherein the particulate material has an average particle size of lessthan 15 microns.
 20. The method of claim 12, wherein the methodcomprises using the composition to seal at least a portion of the tooth.21. The method of claim 12, wherein the method comprises using thecomposition to repair root perforations.
 22. The method of claim 12,wherein the method comprises using the composition to repair rootresorption.
 23. The method of claim 12, wherein the method comprisesusing the composition to fill root ends.
 24. The method of claim 12,wherein the method comprises using the composition to cap at least aportion of the pulp that has been exposed.
 25. The method of claim 12,wherein the method comprises using the composition to line a cavitypreparation where a pulp-exposure is possible.
 26. The method of claim12, wherein the method comprises using the composition to obturate rootcanals.
 27. The method of claim 12, wherein the method comprises usingthe composition to cover a root access opening in a root after apulpotomy has been performed.
 28. The method of claim 12, wherein themethod comprises using the composition to seal a root canal aftergutta-percha has been introduced into the canal.
 29. The method of claim12, wherein the composition further comprises anti-bacterial and/oranti-microbial agents.
 30. The method of claim 29, wherein theanti-microbial agent includes chlorhexidine gluconate.
 31. A dentalcomposition comprising: a) about 1 to about 80% by weight of particulatematerial including: (i) dicalcium silicate; tricalcium silicate; calciumsulfate dehydrate; a carbonate; calcium sulfate; a phosphate; andtricalcium aluminate; and wherein the particulate material has anaverage particle size of less than 15 microns.
 32. The dentalcomposition of claim 31, wherein the particulate material furtherincludes a radiopacifier.
 33. The dental composition of claim 32,wherein the radiopacifier is bismuth oxide.
 34. The dental compositionof claim 31, further comprising b) a liquid carrier selected from thegroup consisting of a water-soluble polymer and water.
 35. The dentalcomposition of claim 35, wherein the water-soluble polymer is selectedfrom the group consisting of polyvinyl alcohols, polyvinyl-pyrrolidone(PVP), partially hydrolyzed polyvinyl acetates, (PVAc), polyacrylic acid(PAA), and polymethacrylic acid (PMA), hyaluronic acid, water-solublepoly-saccharides, poly amino-acids, and mixtures thereof.